This sounds remarkably like a bug I experience every day.  I use
blue-click + drag for regular SystemWindows and, yes, 99% of the time
its after a window had just been spawned, I moved it once with the
blue-click (which invokes halos) and then the next red-click causes
the window to jump.

It happened in one of my Squeak videos:  this 10 seconds from 3:53 --
4:03 shows it.

   https://youtu.be/rbfIGOuN_fI?t=233

Kind of jarring whenever it happens, I wonder if the distance thrown
is related to the drag distance...

On Fri, Mar 1, 2019 at 12:48 PM K K Subbu <kksubbu.ml at gmail.com> wrote:
>
> On 01/03/19 1:30 PM, karl ramberg wrote:
> > The bug is present on latest 5.3 trunk image. I haven't tested on
> > older images.
> >
> > Bug appear when I click the mouse wheel (bring up halo) and drag at
> > the same time on a SketchMorph.
>
> I see it now. It happens only with freshly drawn sketch. I could
> reproduce it in both 5.2 and 5.3 alpha:
>
>   * World Menu -> new morph -> make new drawing
>   * draw any shape
>   * middle-click hold, the halo appears, drag and the sketch moves to
> origin.
>   * If we drag the sketch to a new place and repeat, the sketch does not
> move to origin.
>
> This looks like a initialization error.
>
> > I'll take a look at the other bugs you reported.
> Thanks.
>
> Regards .. Subbu
>